A known method for making a lead by connecting a metal and an electric conductive plastic is disclosed in a Japanese Patent Application published as Toku-Kai-Hei 10(1998)-237315 published in 1998. In this known method, the lead (made of metal material) is embedded in the electric circuit (made of electric conductive plastic material) at the same time the circuit is formed by injection molding.
Other known methods involve, for examples, connecting the lead to the electric conductive plastic material by soldering or using electric conductive adhesive agent (Ag system) and connecting the lead to the electric conductive plastic material by mechanically pushing the lead into the electric conductive plastic material.
However, these known methods have a variety of drawbacks and disadvantages. In the case of the method involving simultaneous connection during injection molding of the circuit, it is necessary for the electric components to be disposed in the mold at the injection molding. This can restrict the location or arrangement of the connecting formation and may result in increasing the complexity of the connecting process.
With the method involving pushing the lead into the circuit, the connection strength is relatively weak compared to the soldering method, thus possibly resulting in a separation of the connecting portion, especially of the electric connecting portion, due to vibrations and heat impact. as a result, the reliability of the connection cannot be ensured.
Further, to cope with environmental protection, non-lead or lead-free materials have been used for soldering. When using such lead free materials for soldering, the melting point of the lead-free materials tends to be higher when soldering and the electronic components may be destroyed due to the high temperature of the soldering process.
In light of the foregoing, a need exists for a method and product not as susceptible to the same disadvantages and drawbacks as those discussed above.
Thus, a need exists for a connecting method for connecting a metal material with an electric conductive plastic material, as well as a product produced by such a method. Further, a need exists for a method and product in which a metal material is reliably connected with an electric conductive plastic material.